This invention relates to a novel comosition of matter which is useful as a liquid monopropellant for rocket motors. More particularly, this invention concerns itself with an energetic, thermally initiated, liquid, polynitro aliphatic monopropellant composed of a mixture of a geminate dinitro compound and a fluorodinitromethyl compound.
The increased interest in the use of rockets, missiles and other propulsion type devices has created a demand for more efficient propellant compositions. As is known, the primary function of a propellant is to impart motion to an object by means of a combustion reaction which transforms the propellant, either liquid or solid, into a gaseous form. The mechanism for effecting combustion differs for the various classes and types of propellants. In liquid propellants, flow rates, vaporization rates, droplet size and compositional content are important factors in the combustion reaction. Also, storage problems are of importance when using bipropellant compositions since the liquid fuel and liquid oxidizer components must be maintained in separate facilities until they are mixed in the combustion chamber.
Generally, liquid bipropellant compositions have greater performance capabilities than liquid monopropellants. However, the simplicity of using a monopropellant system and the elimination of its dual storage and flow facilities oftentimes is sufficient to justify the use of a monopropellant. This has been true even with present day state-of-the-art monopropellants such as hydrazine whose use has increased substantially over the years. The increase is due, primarily, to the development of a catalyst that will initiate and maintain its decomposition characteristics over a series of restarts. As a consequence, this fully characterized compound has found wide application and use in a number of aerospace systems. However, hydrazine is unsuitable for many potential monopropellant applications because of its low performance, high freezing point, and the catalyst requirement for the decoposition.
The economic benefits of an increased spacecraft payload resulting from the use of higher performance monopropellants is both obvious and significant. For example, a 20% increase in I.sub.s would permit a 17% increase in payload for a 2000-pound spacecraft. Less obvious is the benefit derived from a propellant having a low freezing point. This would permit the removal of the many heaters necessary to prevent hydrazine from freezing and, thereby, increase the usable payload. Also, additional benefits would accrue from a noncatalytic decomposition mode such as increased reliability, predictable and ensured service life, and elimination of high catalyst cost.
As a consequence, a research effort was initiated in an attempt to provide a new and improved monopropellant composition in order to take advantage of the benefits referred to above. This effort resulted in the discovery of the propellant composition of this invention which is capable of a theoretical performance at least 10 percent greater than anhydrous hydrazine. Also, it is characterized by a lower freezing point than hydrazine and is capable of decomposition without the need for catalysts.